I have to mention that all of the races have access to several siege weapons, in categories like: siege ladders, siege towers, battering rams, and catapults. Each race has a radically different approach/visuals for these siege weapons though.

Lets look at Elfs for example:
-Elven siege ladders is actually a plant which grows from the ground in front of the enemy walls
-Elven catapult is an animated tree, which also has an ability to fight on it`s own by charging and crashing enemies
-Elven siege tower/battering ram are both the same unit - War Tree, which also serves as a mobile archer tower/melee fighting unit.